Guy:
I think you are better off sending your unit off to one of the specialists here (either directly or ask for referal). These things are old, and as Martin and others have pointed out it could very well be capacitors that have gone bad. Any "swap" you may do will likely be prone to the same problem or may exhibit it soon. The key is finding someone that knows how to repair the pickups at the board levels since B&O is no longer able to provide replacements.
Also swapping is not easy. This is because the cosemetic piece (the black bottom plate) is glued onto the top of the CD transport. Swapping the assembly will involve transfering that piece over. Its not as straight forward as plug and replace.
Derek